Zimmerman’s Power

Last night, a superstar stepped on to the field for the Washington Nationals. In the very first inning, after yet another feat of strength, the player had 40,000 strong standing, roaring, clamoring for more.

Huh? Oh yeah. That Strasburg guy was pretty good, too. But I was referring to Washington’s other franchise pillar, Ryan Zimmerman.

The fourth overall pick out of the University of Virginia in the 2005 draft, Zimmerman zipped through the minors, reaching the show the very same summer that he was drafted. Over the 2006-2008 seasons, he combined spectacular defense with a quality bat, averaging about +10.3 UZR per 150 defensive games with a 110 wRC+. Zimmerman compiled 3.9 Wins Above Replacement per season over that time frame, though that total was stunted somewhat by a left shoulder injury in ’08 that put him on the shelf for two months.

Since then, Zimmerman has taken his game to another level. He had 6.6 WAR in 2009, tied with Adrian Gonzalez for 9th among position players. This season, Zimmerman’s 3.2 WAR total trails only Justin Morneau, Robinson Cano and Alex Rios.

The 25-year-old third baseman is swift as ever with the glove, posting a +14.1 UZR/150 last season and a +24.7 UZR/150 in 2010. But it’s his bat that has taken a great leap forward — Zimmerman had a 132 wRC+ in 2009 and currently owns a 169 wRC+ this year.

Zimmerman’s power numbers have spiked since the beginning of the ’09 season. He had Isolated Power figures of .184, .191 and .159 over the 2006-2008 campaigns. Last year, his ISO climbed to .233. This season, it’s up to .282. Zimmerman’s home run per fly ball rate, 11.4-11.5 percent from 2006-2008, was 15.9 percent in 2009 and sits at 20.3 percent in 2010.

With the exception of 2009, Zimmerman has always posted excellent totals when pulling the ball to the left side. This season, he has been off-the-charts good..

Also, his power to center and the opposite field has surged:

Zimmerman’s pop up rate to the right side has fallen each year of his career, which certainly helps his opposite field numbers. Take a look at his infield/fly ball rates when hitting to the right side:

A more powerful Zimmerman is getting fewer pitches thrown within the strike zone. His percentage of in-zone offerings was right around the major league average each season prior to 2010. But that mark has fallen this year:

His walk rate has climbed as well — Zimmerman took a free pass in 8.2 percent of his plate appearances from 2006-2008, but walked 10.4 percent last season and 14.3 percent in 2010. He is getting more intentional walks (nine last year, four so far this year). That could affect his zone percentage a bit, too — without the intentionals, Zimmerman’s Zone% is around 46.4, though that’s still below the MLB average. Intentional walks or not, Zimmerman’s unintentional walk rate is up. It was 7.6 percent from 2006-2008, 9.1 percent in 2009 and is 12.4 percent in 2010.

Last year, Dave Cameron showed that there’s an inverse relationship between the percentage of fastballs a hitter sees and his ISO: the more pop a player has, the fewer fastballs he gets. That has been the case for Zimmerman. He got a heater a career-high 61.4 percent in 2007, and saw fastballs 59.9 percent in 2008 and 59.1 percent in 2009. This year, he’s getting challenged 55.3 percent.

Perhaps there’s some game theory going on here: Zimmerman mashed fastballs last season (+1.32 runs per 100 pitches seen), and pitchers have responded by throwing more breaking and off-speed stuff this season. Zimmerman’s performance against fastballs in 2010 is still good but has fallen (+0.51 runs/100), while his performance against more frequently thrown breaking balls and changeups has improved. Maybe Zimmerman is looking for something that bends or tumbles more often.

Will he continue to hit for this type of power? My guess would be that Zimmerman keeps some of the gains that he has made, but not all of them. According to Hit Tracker Online, Zimmerman leads the majors in “Just Enough” home runs, with six. A “Just Enough” home run, per the definition on the site, “means the ball cleared the fence by less than 10 vertical feet, OR that it landed less than one fence height past the fence. These are the ones that barely made it over the fence.”

Zimmerman’s rest-of-season ZiPS projects a .227 ISO, which seems reasonable. He has been beating the snot out of the baseball for too long to consider it a total fluke, though I’d bet that he won’t keep hitting a homer two-thirds of the time that he pulls a fly ball.

Be happy, Nats fans — a superstar debuted on the mound last night, but remember that you guys have one at the hot corner, too.